JP3747478B2 - Contact charging device - Google Patents

Description

【００３１】
で示されるアゾ化合物０．４５重量部、ポリエステル樹脂（バイロン２００：東洋紡績社製）０．４５重量部、及びシクロヘキサノン５０重量部をサンドグラインダーに入れて２４時間分散し感光塗液を得た。この時の感光塗液の粘度は２０℃で２０ｃｐであった。 この塗液を、表面にバイト切削加工を施したアルミニウム製円筒基体表面にディッピング法を用いて塗布し、乾燥後の膜厚が０．３μｍの電荷発生層を形成した。ここで使用した円筒基体はマグネシウムを０．７重量％、硅素を０．４重量％含有したアルミニウム合金であり、また、乾燥条件は２０℃の循環空気中で３０分間とした。
【００３２】
次いでこの電荷発生層上に、下記構造式：
【００３３】
【化２】

【００３４】
で示されるスチリル化合物１０重量部、ポリカ−ボネ−ト樹脂（パンライトＫ−１３００：帝人化成社製）７重量部、を１，４−ジオキサン４０重量部から成る溶媒中に溶解させた塗液をディッピング法を用いて塗布し、乾燥して、膜厚３２μｍの電荷輸送層を形成した。この時の塗液の粘度は２０℃で２４０ｃｐであり、また、乾燥条件は１００℃の循環空気中で３０分間とした。
【００３５】
以上のようにして導電性基体上に、電荷発生層、電荷輸送層を順次積層した機能分離型有機感光体を作製し、感光体ドラム１として用いた。
【００３６】
なお、本発明の実施例に使用した感光体は、上記の如き機能分離型有機感光体であるが、本発明を適用し得る感光体は、当然これに限定されるものではない。
【００３７】
感光体感度域について言えば、半導体レーザー（７８０ｎｍ）光学系やＬＥＤアレイ（６８０ｎｍ）光学系等の長波長光を用いた作像システムにおいては、長波長域に感度を有する感光体を使用すればよいし、例えば、液晶シャッターアレイ、ＰＬＺＴシャッターアレイ等で可視光を光源とした作像システム、可視光レーザーを光源とした作像システム、螢光体発光アレイを光源とした作像システム、或るいは、前述の如き一般の複写機で常用されている可視光とレンズ・ミラー光学系によるアナログ作像システムにおいては、上記の如き可視域に感度を有する感光体を使用すれば良い。
【００３８】
また、感光体構成について言えば、上記感光体は電荷発生層の上に電荷輸送層を分離して設けた機能分離型有機感光体であるが、電荷輸送層の上に電荷発生層を設けた所謂逆積層型の感光体であっても良いし、電荷発生機能と電荷輸送機能とを合わせ持つ所謂単層型構成の感光体であってもよい。また、電荷発生材料、電荷輸送材料、結着樹脂、添加剤等も、公知の材料を目的に応じて適宜選択すればよい。また、感光材料についても有機材料に限る事なく、酸化亜鉛、硫化カドミウム、セレン系合金、非晶質硅素系合金、非晶質ゲルマニウム系合金、等の無機材料を使用してもよい。
【００３９】
本発明に適用可能な感光体は、更に、耐久性、耐環境特性等を改善するために表面保護層を設けたものであっても良いし、帯電性能、画質、接着性等を改善するために下引き層を設けたものであってもよい。そのような表面保護層或るいは下引き層の材料としては、紫外線硬化性樹脂、常温硬化性樹脂、熱硬化性樹脂等の樹脂、その樹脂中に抵抗調整材料を分散した混合樹脂、金属酸化物、金属硫化物等を真空中で蒸着法やイオンプレーティング法等で薄膜化した真空薄膜材料、プラズマ重合法を用いて作製された不定形炭素膜、不定形炭化硅素膜等々を使用する事ができる。
【００４０】
本発明に適用可能な感光体の基体材料は、表面が導電性を有する支持体であれば特に限定は受けず、また、形状も円筒形以外に平板状であっても良いし、ベルト状であっても良い。さらに、基体表面に粗面化処理、酸化処理、着色処理等が施されたものであっても良い。
【００４１】
前記現像装置３において使用するトナーは正帯電型の不定形状のスチレンアクリル系トナーである。以下に該トナーの作製方法について述べる。
【００４２】
まず、スチレン−ｎ−ブチルメタクリレート樹脂（軟化点：１３２℃、ガラス転移温度：６０℃）１００重量部に対し、カーボンブラック（Ｍｏｇｕｌ−Ｌ：キャボット社製）８重量部とニグロシン系染料（ボントロンＮ−０１：オリエント化学社製）５重量部と無極性ポリプロピレン（６０５Ｐ：三洋化成社製）３重量部とを計量し、ボールミルで充分混合した。次いでこの混合物を１４０℃で加熱した３本ロール上で充分混練し、混練物を放置冷却後、粗粉砕し、更にジェットミルで微粉砕した。この微粉砕物を風力分級し、平均粒径７．５μｍの正帯電型の不定形状のトナーを得、本発明の実施例で使用するに際しては、流動性を付与する目的で、トナー１００重量部に対して疎水性シリカ（Ｒ−９７４：日本アエロジル社製）０．２重量部による後処理をヘンシェルミキサーで行った。
【００４３】
上記トナーはキャリア粒子と混合して、前記現像装置３に投入し、現像剤として使用した。以下に該キャリアの作製方法について述べる。
【００４４】
まず、ポリエステル樹脂（タフトンＮＥ１１１０：花王社製）１００重量部に対し、カーボンブラック（ＭＡ＃８：三菱化成工業社製）２重量部と磁性粉（ＭＦＰ−２：ＴＤＫ社製）３００重量部とを計量添加し、ヘンシェルミキサーで充分混合した。得られた混合物を２軸押し出し機で充分混練し、冷却後粗粉砕した。粗砕物をジェットミル粉砕機と風力分級機で微粉砕及び分級し、平均粒径２μｍの磁性粉含有ポリマー微粒子を得た。
【００４５】
次いで、フェライト粒子Ｆ−２５０ＨＲ（平均粒径５０μｍ：パウダーテック社製）１００重量部に対し、前記磁性粉含有ポリマー微粒子１０重量部を添加し、オングミルＡＭ−２０Ｆ（ホソカワミクロン社製）で回転数２５００ｒｐｍで４０分間処理し、平均粒径５５μｍのキャリア中間体を得た。更に該キャリア中間体をサフュージングシステム（日本ニューマチック工業社製）を用いて４００℃で加熱処理を行い、平均粒径５５μｍのキャリアを得た。
【００４６】
上記トナーとキャリアをトナー濃度７重量％となるように混合撹拌後、前記現像装置３に投入し、図示しないトナー濃度検知器並びにトナー補給装置により、トナー濃度を常に７±１重量％を維持しながら作像に供した。
【００４７】
本発明の実施例では現像剤として、正帯電型の不定形状の黒色トナーと上記キャリアを用いたが、本発明に適用可能な現像剤はこれに限られるものではない。
【００４８】
感光体の極性や使用する作像プロセスに応じて、負帯電型トナー、透光性トナー、磁性トナー、鉄粉キャリア、バインダ型キャリア、樹脂コートキャリア、一成分現像方式、反転現像方式、等を適宜選択して使用する事が可能である。
【００４９】
トナーの色彩については、黒トナーのみならずイエロー、マゼンタ、シアン等のカラートナーを適宜選択して使用することが可能であるし、トナー形状も不定形であってもよいし、特定の形状、例えば球形トナー、結晶形トナー等を使用する事も可能である。キャリアについては、粉体をキャリアとせずに、例えば、導電性ブラシ、導電性ローラー等にキャリアに必要な機能を担わせた現像システムを適宜選択して使用する事も可能である。更に、現像剤としては流動性やクリーニング性能を向上させる目的から、ポリ弗化ビニリデン樹脂、テフロン樹脂、ＰＭＭＡ樹脂等の粉末やビーズを滑剤として混入したものを使用することも可能である。
【００５０】
次に前記複写機における帯電装置２の基本構成を図２及び図３に基づいて説明する。図２は帯電装置２の横断面を、図３は帯電装置２の縦断面を示したものである。該帯電装置２は導電性支持体１１の上に、導電性弾性体層１２、導電性樹脂層１３を順次積層した構成である。
【００５１】
本発明実施例の導電性支持体１１には、直径８ｍｍのＳＵＳ３０３製の金属シャフトを用いた。
【００５２】
尚、導電性支持体１１には図示しない電源より適当な帯電電圧が印加される。
【００５３】
例えば、絶対値で０．８〜２．０Ｋｖの直流電圧が印加される。そして、同電圧には交流電圧が適宜重畳されてもよい。
【００５４】
次いで該導電性支持体１１上に、肉厚５ｍｍのエチレンプロピレンゴムを主体としたゴム層を設けた導電性弾性体層１２を設けた。このエチレンプロピレンゴム材はゴム成形の常法、即ち、素練り、配合、混練、熟成、ウォームアップ、シーティング、成形、締めつけ、加硫、放冷、研摩、等の工程を経て、ローラー形状に成形した。この時、配合時に導電性炭素を主体とする導電剤、並びに、ジオクチルフタレートを主体とする可塑剤を適宜調整し、成形後の電気抵抗率を２×１０⁵Ωｃｍに揃えたＪＩＳ−Ａ硬度が３０°と２２°の試料を作製した。
【００５５】
次いで導電性弾性体層１２上に、チューブ成形法を用いて作製した樹脂チューブを導電性樹脂層１３として設けた。チューブ材料にはインフレーション法を用いて作製されたポリ塩化ビニルフィルムを使用した。チューブ被覆に際しては、チューブ内径を１７．５ｍｍとし、チューブを風圧にて膨張させながら導電性弾性体層１２を導電性支持体１１上に設けた直径１８ｍｍの上記ローラーを挿入する外嵌被着処理を用いた。
【００５６】
導電性樹脂層１３に用いたポリ塩化ビニルフィルムは、フィルム原料中に抵抗調整用に混入した導電性炭素微粉末の種類及び添加量、伸び率調整用に混入した可塑剤の種類及び添加量、これら原料の混練条件とインフレーション加工条件、フィルム膜厚、等を調整する事により、電気抵抗率を３×１０⁸Ωｃｍに揃えな がら、１ｃｍ幅切片における１０％伸び加重がそれぞれ、３０ｇｆ、１００ｇｆ、３００ｇｆ、５００ｇｆ及び７００ｇｆ、である試料を作製した。別に比較実験用には同様にして作製した１ｃｍ幅切片における１０％伸び加重がそれぞれ、１０ｇｆ、及び９００ｇｆ、である試料を作製した。 ここで導電性樹脂層１３についての、１ｃｍ幅切片における１０％伸び加重について、その測定方法を説明する。
【００５７】
まず上記の如く作製された、導電性支持体１１上に、導電性弾性体層１２、導電性樹脂層１３を順次積層してなる帯電装置２について、導電性樹脂層部分に適当な刃物で切り込みを入れ、幅１ｃｍ×長さ６ｃｍの導電性樹脂層切片を採取した。この切片の長手方向の両端よりそれぞれ５ｍｍの部分でチャッキングし、長手方向に幅１ｃｍ×長さ５ｃｍの部分について引っ張り加重を付与し、その時の試料の伸びが５ｃｍの測定長さに対して１０％となる５ｍｍとなった時の加重を求め、それをこの帯電装置２の導電性樹脂層１３における１ｃｍ幅切片における１０％伸び加重Ｆｇｆとした。
【００５８】
ここで、試料の都合により導電性樹脂層切片を上記寸法で採取できない場合には、矩形状に採取した切片幅Ｗｃｍ、引っ張り試験部分の切片長Ｌｃｍ、引っ張り加重Ｔｇｆ、引っ張り加重を負荷した状態での引っ張り試験部分の切片長Ｌ’ｃｍより、次式；
【００５９】
【数１】

【００６０】
を用いて、１ｃｍ幅切片における１０％伸び加重Ｆｇｆと見做す。
【００６１】
なお、試料の採取に際しては、導電性樹脂層切片を採取後の導電性弾性体層について、ＪＩＳ−Ａ硬度を測定し、その値が導電性弾性体層本来の３０°以下となっている事を確認し、導電性樹脂層が本発明の主旨通りに採取できた事を確認した。また、導電性樹脂層としてチューブ材料を用いた場合には、外嵌被着処理前のチューブ材料について直接伸び加重を求める事も可能であるが、外嵌被着処理時の材料の変成による伸び加重の変化も無視できない事から、本評価では最終形状の試料から導電性樹脂層切片を切り出す方法を用いた。
【００６２】
次に前記複写機における帯電装置２の別の実施例の構成を図４及び図５に基づいて説明する。図４は帯電装置２の横断面を、図５は帯電装置２の縦断面を示したものである。該帯電装置２は導電性支持体３１の上に、導電性弾性体層３２、導電性樹脂層内層３３、導電性樹脂層外層３４を、順次積層した構成である。
【００６３】
この構成の特徴は導電性樹脂層を内層と外層の複数層構成にした処にあるが、具体的には、導電性支持体３１として前述と同様の直径８ｍｍのＳＵＳ３０３製の金属シャフトを、導電性弾性体層３２として前述と同様のＪＩＳ−Ａ硬度３０°と２２°の肉厚５ｍｍのエチレンプロピレンゴムを主体としたゴム層を、導電性樹脂層内層３３として前述と同様の製法により作製されたポリ塩化ビニルフィルムを、そして導電性樹脂層外層３４として四フッ化エチレン樹脂層を、順次積層した帯電装置２を作製した。この四フッ化エチレン樹脂層は、市販の四フッ化エチレン樹脂塗液（日本アチソン社製：エムラロン３４５）を塗液粘度２５０〜３００ｃｐの下でスプレー塗布した後、１００〜１６０℃で３０〜１２０分間乾燥する事により作製した。
【００６４】
ここで、前述の如きポリ塩化ビニルチューブの作製条件に加え、四フッ化エチレン樹脂層の塗液粘度、乾燥温度、乾燥時間、スプレー条件、膜厚、等を調整する事により、二層構成を有する導電性樹脂層全体の電気抵抗率を３×１０⁸Ωｃ ｍに揃えながら、１ｃｍ幅切片における１０％伸び加重がそれぞれ、３０ｇｆ、１００ｇｆ、３００ｇｆ、５００ｇｆ及び７００ｇｆ、である試料を作製した。
【００６５】
別に比較実験用には同様にして作製した１ｃｍ幅切片における１０％伸び加重がそれぞれ、１０ｇｆ、及び９００ｇｆ、である試料を作製した。
【００６６】
以上のようにして作製された各種帯電装置２を図１に主要構成を示した複写機に搭載し、作像し、画質評価を行った。以下にその評価方法を具体的に記す。
【００６７】
帯電装置２を感光体１に接触による悪影響が生じない２ｋｇｆにて圧接し、感光体の回転周速度、即ち、従動回転している帯電装置２の回転周速度として高速領域の複写機では常用の範囲の２２ｃｍ／ｓｅｃ、３８ｃｍ／ｓｅｃ、６０ｃｍ／ｓｅｃを選び、印加電圧を概ね−１．０〜−１．２ｋＶの範囲で調整しながら感光体表面を−６００Ｖに初期帯電した。この時感光体表面電位の測定には市販の表面電位計（ＴＲＥＫ社製表面電位計ＭＯＤＥＬ３４４）を用いた。
【００６８】
次いで濃度０．４のハーフ原稿を原稿台に載置し図１の位置Ｌより露光した後、現像器３により現像し、得られたトナー像を濃度０．０３の転写紙に転写して評価用の画像サンプルを得た。この時、露光量は適宜調節し、以下に述べる画像濃度評価での最大画像濃度値が１．０となるようにした。
【００６９】
得られた画像サンプルは、市販の画像濃度計（コニカ社製サクラマイクロデンシトメータＭｏｄｅｌＰＤＭ−５ＴｙｐｅＢＲ）を用いて、感光体周方向に対応した長さ１０ｃｍの走査方向において、倍率５０倍、走査速度５０μｍ／秒、測定面積１０平方μｍの条件下で画像濃度の測定に供した。この時測定された最大画像濃度（１．０）と最小画像濃度から画像濃度差を求め、官能評価と対応付けた。
【００７０】
ここで画像濃度差が０．２以内の画像サンプルは、視覚的にもローラー弾みによる画像濃度ムラが認識できない画像と言え、このような画像をランクＡと称する事とした。画像濃度差が０．２を越え０．３５以内の画像サンプルは、視覚的に僅かではあるがローラー弾みによる画像濃度ムラが感じられるものの実用上は問題ない画像と言え、このような画像をランクＢと称する事とした。画像濃度差が０．３５を越える画像サンプルは、視覚的にもローラー弾みによる画像濃度ムラが明視距離で認識可能である事から実用上好ましくない画像と言え、このような画像をランクＣと称する事とした。
【００７１】
別途、図１に主要構成を示した複写機において、Ａ４紙８万枚を通紙する耐久試験を行い、帯電装置２の耐久性を評価した。耐久試験前後での帯電装置２の表面を光学顕微鏡にて観察し、表面形態に変化が認められず充分な耐久性を示した帯電装置をランクＸ、微小なクラックの発生が認められたものの導電性弾性体層の露出には至らなかった帯電装置をランクＹ、微小剥離が発生し導電性弾性体層の露出部分が僅かにでも観察された帯電装置をランクＺと称する事とした。
【００７２】
表１及び表２に得られた各種帯電装置２についての評価結果を示した。表１は図２及び図３に示した導電性樹脂層が単層で設けられた帯電装置２についての評価結果、表２は図４及び図５に示した導電性樹脂層が複数層設けられた帯電装置２についての評価結果である。表中、伸び加重とは、前記導電性樹脂層の１ｃｍ幅切片における１０％伸び加重の事を言う。
【００７３】
【表１】

【００７４】
【表２】

【００７５】
以上の結果から、導電性支持体上にＪＩＳ−Ａ硬度３０°以下の導電性弾性層を有し、かつ、周速２０ｃｍ／ｓｅｃ以上で回転して用いられる高速領域におけるローラー型接触帯電装置では、前記導電性弾性体層上に１ｃｍ幅切片における１０％伸び加重が７００ｇｆ以下の導電性樹脂層を設ける事によって、その導電性樹脂層の構成が単層積層のいかんにかかわらず、ローラー弾みによる画像濃度ムラがランクＡ及びランクＢで示した実用上問題のない画像が得られる事が分かる。更に、１ｃｍ幅切片における１０％伸び加重が５００ｇｆ以下の導電性樹脂層を設けた場合には、その導電性樹脂層の構成が単層積層のいかんにかかわらず、ローラー弾みによる画像濃度ムラがランクＡで示した最適な画像が得られる事が分かる。
【００７６】
一方、耐久性と言う別の目的からは、１ｃｍ幅切片における１０％伸び加重が３０ｇｆ以上の導電性樹脂層を設ける事によって、その導電性樹脂層の構成が単層積層のいかんにかかわらず、ローラー表面形態が耐久試験後もランクＸ及びランクＹで示した実用上問題のない性能を有する事が分かる。更に、１ｃｍ幅切片における１０％伸び加重が１００ｇｆ以上の導電性樹脂層を設ける事によって、その導電性樹脂層の構成が単層積層のいかんにかかわらず、ローラー表面形態が耐久試験後もランクＸで示した最適な性能を有する事が分かる。
【００７８】
【発明の効果】
本発明によると、高速度の画像形成装置に使用した場合においても、接触帯電装置特有のローラー弾みの発生を防止することができるので、画像濃度ムラが生じにくく安定して良好な帯電を行うことができ、信頼性の高い接触帯電装置を提供することができる。
【図面の簡単な説明】
【図１】 本発明帯電装置を組み込み使用する複写機の主要部分の一例を示す概略構成図である。
【図２】 本発明に係る帯電装置の基本構成の横断面図である。
【図３】 本発明に係る帯電装置の基本構成の縦断面図である。
【図４】 本発明に係る帯電装置の別の構成の横断面図である。
【図５】 本発明に係る帯電装置の別の構成の縦断面図である。
【符号の説明】
１：感光体ドラム、２：帯電装置、３：現像装置、４：転写チャージャー、５：クリーニング装置、６：イレーサー、７：中間ローラー対、８：タイミングローラー対、９：搬送ベルト、１１，３１，１０１：導電性支持体、１２，３２，１０２：導電性弾性体層、１３，１０３：導電性樹脂層、３３：導電性樹脂層内層、３４：導電性樹脂層外層、１００：コイルバネ[0001]
[Industrial application fields]
The present invention relates to a charging device for an image forming apparatus such as an electrophotographic copying machine, a printer, or a facsimile.
[0002]
[Prior art]
In image forming apparatuses such as electrophotographic copying machines, printers, facsimiles, etc., an electrostatic latent image carrier such as a photosensitive drum is charged by a charging device, and an image is exposed to the charged area to form an electrostatic latent image. The latent image is developed into a visible image, which is transferred to a transfer material and fixed.
[0003]
Various types of charging devices are known, but broadly classified as corona charging devices using corona discharge, such as corotron, scorotron, and sawtooth electrode array methods, and rollers, brushes, films, and belts. The charging member can be divided into contact-type charging devices that contact the surface of the electrostatic latent image carrier with a charging member having a shape such as the above.
[0004]
A charging device using corona discharge has the advantage of being able to perform stable charging, but it involves the generation of a large amount of ozone, which can cause deterioration of the electrostatic latent image carrier and adversely affect the human body. In addition, a contact charging device that generates significantly less ozone than a corona charging device has attracted attention.
[0005]
In particular, a contact charging device having a roller shape has been put into practical use by a functionally sharing configuration in which a conductive elastic layer and a conductive resin layer are sequentially laminated on a conductive support.
[0006]
Here, the conductive support shares a voltage supply function for applying a high voltage to the entire roller, a pressure application function for ensuring contact between the roller and the electrostatic latent image carrier, and the like. The elastic layer secures the conduction between the roller and the electrostatic latent image carrier with a wide nip width, as well as a conduction ensuring function to prevent a voltage drop from the inside of the roller to the outside by setting an appropriate electrical resistance value. For example, the conductive resin layer has a breakdown function for preventing abnormal discharge of the roller in the defective portion of the electrostatic latent image carrier by developing an appropriate electric resistance value, and developing the conductive resin layer. It functions as a releasable function for preventing adhesion of agents, dust, and the like, and an anti-abrasion function for preventing damage due to rubbing against the electrostatic latent image carrier.
[0007]
However, although such a roller-type contact charging device has been put to practical use in a region where the process speed is low, a high-speed region where low ozone is strongly desired due to high ozone generation, specifically 35 sheets. In a region where the process speed (peripheral speed of the electrostatic latent image carrier) is 22 cm / sec or more, which is an area of at least / min, it has not been put into practical use.
[0008]
JP-A-57-199349 discloses a charging device having a rubber hardness of 20 ° or less, and JP-A-1-179957 discloses a charging device having an ASKER-C hardness of 5 ° to 60 °. No. -191161 discloses charging devices having an ASKER-C hardness of 60 ° or less, but none of them solves the problem in the high speed region described later.
[0009]
[Problems to be solved by the invention]
In the conventional roller-type contact charging device having a laminated structure, it is difficult to ensure stable contact with the electrostatic latent image carrier, so that it is difficult to apply to a high speed region, specifically, a region of 22 cm / sec or more. . That is, the conductive resin layer is randomly provided on the conductive elastic layer, and as the rotational peripheral speed of the roller increases, the conductive property having a high cushioning property is brought about by contact with the electrostatic latent image carrier. When the elastic layer is deformed, the conductive resin layer covering the surface cannot follow the expansion and contraction, and as a result, minute bounces start to occur on the roller, causing striped image noise parallel to the roller longitudinal direction. It was. In order to solve this micro-boundary problem, simply increasing the roller pressing pressure to the electrostatic latent image carrier, image noise is likely to occur at the high-pressure contact portion of the electrostatic latent image carrier, and high pressure For this reason, it is necessary to increase the photoreceptor strength, resulting in an increase in cost.
[0010]
Therefore, the present invention can obtain a good image without generating the above-mentioned minute bounce even in a high-speed region, specifically in a region of 22 cm / sec or more, as compared with a roller-type contact charging device having a conventional laminated structure. It is an object to provide a highly reliable contact charging device.
[0011]
[Means for Solving the Problems]
As a result of repeated studies to solve the above problems, the present inventors have found that the conductive resin layer has a specific elongation even when the contact charging device is used in an image forming apparatus having a process speed of 22 cm / sec or more. As a result, it was found that the fine bounce does not occur and a good image can be obtained and the above-mentioned problems can be solved, and the present invention has been completed.
[0012]
The present invention is a contact charging device having a roller shape, which is used in an image forming apparatus in which the surface movement speed of an electrostatic latent image carrier is 22 cm / sec or more, and has a JIS-A hardness on a conductive support. 30 ° The present invention relates to a contact charging device having the following conductive elastic layer and a conductive resin layer having a 10% elongation load of 30 gf to 700 gf in a 1 cm width section.
[0013]
In the present invention, the 10% elongation load in the 1 cm width section of the conductive resin layer is more preferably 500 gf or less. Moreover, about the lower limit of 10% elongation weight in this 1 cm width section Is From another factor of maintaining mechanical strength (prevention of tearing, tearing, etc. of the conductive resin layer) for use in tactile charging, it is preferably 30 gf or more, more preferably 100 gf or more.
[0014]
As the conductive support in the contact charging device of the present invention, metal materials such as iron, SUS, aluminum, copper, chromium, and titanium can be used.
[0015]
As the conductive elastic layer in the contact charging device, natural rubber, styrene butadiene rubber, nitrile rubber, chloroprene rubber, butyl rubber, ethylene propylene rubber, chlorosulfonated polyethylene, silicone rubber, fluorine rubber, urethane rubber, chlorinated polyethylene, acrylic In rubber materials such as rubber, epichlorohydrin rubber, polybutadiene, polyisoprene, etc., conductive carbon such as powder shape, fiber shape, iron, aluminum, copper, chromium, titanium, tin, zinc, gold, silver, cobalt, Use conductive rubber treated by dispersing metals such as lead and platinum, metal oxides such as antimony oxide, indium oxide and molybdenum oxide, and conductive polymers such as polyacetylene, polypyrrole and polythiophene. Can do.
[0016]
As the conductive resin layer in the contact charging device, polyethylene, polypropylene, ionomer, polyvinyl alcohol, polyvinyl acetate, ethylene vinyl acetate copolymer, poly-4-methylpentene-1, polymethyl methacrylate, polycarbonate, polystyrene, acrylonitrile Methyl acrylate copolymer, acrylonitrile butadiene styrene copolymer, ethylene polyterephthalate, polyurethane elastomer, cellulose nitrate, cellulose acetate, cellulose triacetate, cellulose propionate, cellulose acetate butyrate, ethyl cellulose, regenerated cellulose, nylon 6, nylon 66 , Nylon 11, nylon 12, polyimide, polysulfone, polyethersulfone, polyvinyl chloride, vinyl chloride vinyl acetate copolymer, polyvinyl chloride , Vinylidene chloride vinyl chloride copolymer, vinyl nitrile rubber alloy, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, etc. in plastic film materials, powder shape, fiber shape, etc. Conductive carbon, iron, aluminum, copper, chromium, titanium, tin, zinc, gold, silver, cobalt, lead, platinum, etc. metal, antimony oxide, indium oxide, molybdenum oxide, etc. metal oxide, polyacetylene, A film obtained by conducting a conductive treatment by dispersing a conductive polymer such as polypyrrole or polythiophene can be used.
[0017]
The conductive resin layer may be composed of two or more kinds of materials, or may be composed of two or more layer structures. Such a film can be formed using a coating method, a tube molding method, a heat shrinkable tube method, or the like.
[0018]
The electrical resistivity of the conductive elastic layer in the contact charging device is 10 to prevent a voltage drop. ⁶ Ωcm or less is desirable. The thickness is not particularly limited as long as the JIS-A hardness is 30 ° or less, and the size of the entire contact charging device is within the range of practical handling and mounting conditions. Generally, about 0.5 to 30 mm is conceivable.
[0019]
The electrical resistivity of the conductive resin layer in the contact charging device is 10 ⁷ Ωcm or more 10 ¹¹ Ωcm or less is desirable. Electrical resistivity is 10 ⁷ If it is lower than Ωcm, it becomes difficult to prevent abnormal discharge of the roller at the defective portion of the electrostatic latent image carrier. ¹¹ If it is higher than Ωcm, intermittent discharge due to accumulation of electric charge during discharge on the surface of the conductive resin layer tends to occur. Further, the thickness is not particularly limited, but generally about 10 to 500 μm can be considered in consideration of durability, moldability and the like.
[0020]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
Each of the embodiments described below is used by being incorporated in a copying machine whose main part is shown in FIG. First, a copier whose main part is shown in FIG. 1 will be described.
[0022]
The copying machine shown in FIG. 1 has a photosensitive drum 1 as an electrostatic latent image carrier at the center, and this drum is rotated counterclockwise in the drawing by a driving means (not shown). Around the photosensitive drum, a charging device 2, a developing device 3, a transfer charger 4, a cleaning device 5 and an eraser 6 are sequentially arranged. The charging device 2 is a charging device according to the present invention, and a roller comes into contact with the photosensitive drum 1 by a coil spring 100 as an urging means and can be driven. The pressure contact force is preferably about 0.5 to 3.0 kgf. If it is less than 0.5 kgf, setting for obtaining sufficient contact becomes difficult, and if it is more than 3.0 kgf, a problem of image noise due to contact tends to occur.
[0023]
An optical system (not shown) is disposed above the photosensitive drum 1, and this optical system is a conventional one composed of an exposure lamp, a reflection mirror, an optical lens, a slit, and the like. With this optical system, an image can be exposed on the photosensitive drum 1 from a position L shown in FIG.
[0024]
An intermediate roller pair 7 and a timing roller pair 8 are sequentially arranged on the left side of the photoconductive drum 1 in the drawing, and transfer paper stored in a paper feeding cassette (not shown) can be supplied from a position C shown in FIG. ing.
[0025]
According to this copying machine, the surface of the photosensitive drum 1 is uniformly charged to a predetermined potential by the charging device 2, and an image is exposed to the charged area from the position L by the optical system to form an electrostatic latent image. The electrostatic latent image thus formed is developed by the developing device 3 to become a toner image and moves to a transfer region facing the transfer charger 4.
[0026]
On the other hand, the transfer paper supplied from the position C reaches the timing roller 8 through the intermediate roller pair 7 and is fed into the transfer area in synchronization with the toner image on the photosensitive drum 1. Thus, the toner image on the photosensitive drum 1 is transferred onto the transfer paper by the action of the transfer charger 4 in the transfer area, and this transfer paper is fixed at a position F to be discharged after the toner image is fixed by a fixing device (not shown) by the transport belt 9. It is conveyed in the direction of.
[0027]
After the toner image is transferred onto the transfer paper, the toner remaining on the photosensitive drum 1 is cleaned by the cleaning device 5 and the residual charge is erased by the eraser 6.
[0028]
The system speed of the copying machine (the peripheral speed of the photosensitive drum 1) is variable in the range of 22 to 60 cm / sec, and the developing device 3 is a two-component regular developing device.
[0029]
The photoreceptor drum 1 is a function-separated organic photoreceptor for negative charging, which has a good sensitivity with respect to a specific visibility range. The method for producing the function-separated organic photoconductor will be described below. First, the following structural formula:
[0030]
[Chemical 1]

[0031]
In a sand grinder, 0.45 parts by weight of an azo compound represented by formula (4), 0.45 parts by weight of a polyester resin (Byron 200: manufactured by Toyobo Co., Ltd.) and 50 parts by weight of cyclohexanone were dispersed for 24 hours to obtain a photosensitive coating solution. The viscosity of the photosensitive coating solution at this time was 20 cp at 20 ° C. This coating solution was applied to the surface of an aluminum cylindrical substrate whose surface was subjected to cutting by a dipping method to form a charge generation layer having a thickness of 0.3 μm after drying. The cylindrical substrate used here was an aluminum alloy containing 0.7% by weight of magnesium and 0.4% by weight of silicon, and the drying conditions were 30 minutes in 20 ° C. circulating air.
[0032]
Then, on this charge generation layer, the following structural formula:
[0033]
[Chemical formula 2]

[0034]
A coating liquid in which 10 parts by weight of a styryl compound represented by formula (7) and 7 parts by weight of a polycarbonate resin (Panlite K-1300: manufactured by Teijin Chemicals Ltd.) are dissolved in a solvent comprising 40 parts by weight of 1,4-dioxane. Was applied using a dipping method and dried to form a charge transport layer having a thickness of 32 μm. The viscosity of the coating liquid at this time was 240 cp at 20 ° C., and the drying conditions were 30 minutes in circulating air at 100 ° C.
[0035]
As described above, a function-separated type organic photoreceptor in which a charge generation layer and a charge transport layer were sequentially laminated on a conductive substrate was produced and used as the photoreceptor drum 1.
[0036]
The photoconductor used in the examples of the present invention is a function-separated organic photoconductor as described above. However, the photoconductor to which the present invention can be applied is not limited to this.
[0037]
Speaking of the photosensitive body sensitivity range, in an image forming system using long wavelength light such as a semiconductor laser (780 nm) optical system or an LED array (680 nm) optical system, a photosensitive body having sensitivity in the long wavelength range is used. For example, an imaging system using visible light as a light source, such as a liquid crystal shutter array or a PLZT shutter array, an imaging system using a visible light laser as a light source, an imaging system using a phosphor light emitting array as a light source, or In the analog image forming system using the visible light and the lens / mirror optical system, which is commonly used in the general copying machine as described above, the photosensitive member having sensitivity in the visible region as described above may be used.
[0038]
As for the photoconductor structure, the photoconductor is a function-separated organic photoconductor provided with a charge transport layer separated on the charge generation layer, but the charge generation layer is provided on the charge transport layer. A so-called reverse laminated type photoreceptor may be used, or a so-called single-layer type photoreceptor having both a charge generation function and a charge transport function may be used. In addition, a charge generating material, a charge transport material, a binder resin, an additive, and the like may be appropriately selected from known materials according to the purpose. Further, the photosensitive material is not limited to an organic material, and inorganic materials such as zinc oxide, cadmium sulfide, selenium-based alloy, amorphous silicon-based alloy, and amorphous germanium-based alloy may be used.
[0039]
The photoconductor applicable to the present invention may further be provided with a surface protective layer in order to improve durability, environmental resistance and the like, and in order to improve charging performance, image quality, adhesiveness and the like. May be provided with an undercoat layer. Examples of the material for such a surface protective layer or undercoat layer include ultraviolet curable resins, room temperature curable resins, thermosetting resins and the like, mixed resins in which a resistance adjusting material is dispersed in the resin, metal oxidation Use vacuum thin film materials obtained by thinning materials, metal sulfides, etc. in vacuum by vapor deposition or ion plating, amorphous carbon films produced by plasma polymerization, amorphous silicon carbide films, etc. Can do.
[0040]
The substrate material of the photoreceptor applicable to the present invention is not particularly limited as long as the surface is a support having conductivity, and the shape may be a flat plate other than a cylindrical shape, or a belt shape. There may be. Furthermore, the surface of the substrate may be subjected to roughening treatment, oxidation treatment, coloring treatment, or the like.
[0041]
The toner used in the developing device 3 is a positively charged, irregularly shaped styrene acrylic toner. A method for producing the toner will be described below.
[0042]
First, for 100 parts by weight of styrene-n-butyl methacrylate resin (softening point: 132 ° C., glass transition temperature: 60 ° C.), 8 parts by weight of carbon black (Moul-L: manufactured by Cabot) and nigrosine dye (Bontron N) -01: Orient Chemical Co., Ltd.) 5 parts by weight and non-polar polypropylene (605P: Sanyo Kasei Co., Ltd.) 3 parts by weight were weighed and mixed well with a ball mill. Next, the mixture was sufficiently kneaded on three rolls heated at 140 ° C., the kneaded product was allowed to cool, coarsely pulverized, and further finely pulverized with a jet mill. This finely pulverized product is classified by air to obtain a positively charged irregularly shaped toner having an average particle diameter of 7.5 μm. When used in the examples of the present invention, 100 parts by weight of toner is used for the purpose of imparting fluidity. On the other hand, post-treatment with 0.2 part by weight of hydrophobic silica (R-974: manufactured by Nippon Aerosil Co., Ltd.) was performed with a Henschel mixer.
[0043]
The toner was mixed with carrier particles, charged into the developing device 3, and used as a developer. A method for manufacturing the carrier will be described below.
[0044]
First, 2 parts by weight of carbon black (MA # 8: manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) and 300 parts by weight of magnetic powder (MFP-2: manufactured by TDK) per 100 parts by weight of polyester resin (Tufton NE1110: manufactured by Kao Corporation) Was weighed and mixed well with a Henschel mixer. The obtained mixture was sufficiently kneaded with a twin screw extruder, cooled and coarsely pulverized. The coarsely pulverized product was finely pulverized and classified with a jet mill pulverizer and an air classifier to obtain magnetic powder-containing polymer fine particles having an average particle diameter of 2 μm.
[0045]
Next, 10 parts by weight of the magnetic powder-containing polymer fine particles are added to 100 parts by weight of the ferrite particles F-250HR (average particle size 50 μm: manufactured by Powdertech), and the rotational speed is 2500 rpm using ANGMILL AM-20F (manufactured by Hosokawa Micron). For 40 minutes to obtain a carrier intermediate having an average particle size of 55 μm. Further, the carrier intermediate was subjected to heat treatment at 400 ° C. using a surfing system (manufactured by Nippon Pneumatic Industry Co., Ltd.) to obtain a carrier having an average particle size of 55 μm.
[0046]
The toner and the carrier are mixed and stirred so that the toner concentration becomes 7% by weight, and then charged into the developing device 3, and the toner concentration is always maintained at 7 ± 1% by weight by a toner concentration detector and a toner replenishing device (not shown). While used for image formation.
[0047]
In the examples of the present invention, positively charged irregularly shaped black toner and the carrier are used as the developer, but the developer applicable to the present invention is not limited to this.
[0048]
Depending on the polarity of the photoconductor and the image forming process used, negatively charged toner, translucent toner, magnetic toner, iron powder carrier, binder type carrier, resin coated carrier, one-component development system, reversal development system, etc. It is possible to select and use as appropriate.
[0049]
Regarding the color of the toner, not only black toner but also color toners such as yellow, magenta, and cyan can be appropriately selected and used, and the toner shape may be indefinite, or a specific shape, For example, spherical toner, crystal toner, or the like can be used. As for the carrier, without using powder as a carrier, for example, a developing system in which a conductive brush, a conductive roller or the like has a necessary function for the carrier can be appropriately selected and used. Further, for the purpose of improving fluidity and cleaning performance, it is also possible to use a developer in which powders or beads such as polyvinylidene fluoride resin, Teflon resin, PMMA resin or the like are mixed as a lubricant.
[0050]
Next, the basic configuration of the charging device 2 in the copying machine will be described with reference to FIGS. FIG. 2 shows a transverse section of the charging device 2, and FIG. 3 shows a longitudinal section of the charging device 2. The charging device 2 has a configuration in which a conductive elastic layer 12 and a conductive resin layer 13 are sequentially laminated on a conductive support 11.
[0051]
A metal shaft made of SUS303 having a diameter of 8 mm was used for the conductive support 11 of the embodiment of the present invention.
[0052]
An appropriate charging voltage is applied to the conductive support 11 from a power source (not shown).
[0053]
For example, a direct current voltage of 0.8 to 2.0 Kv in absolute value is applied. Then, an AC voltage may be appropriately superimposed on the voltage.
[0054]
Next, a conductive elastic layer 12 provided with a rubber layer mainly composed of ethylene propylene rubber having a thickness of 5 mm was provided on the conductive support 11. This ethylene-propylene rubber material is molded into a roller shape through processes such as kneading, blending, kneading, aging, warm-up, sheeting, molding, clamping, vulcanization, cooling, polishing, etc. did. At this time, a conductive agent mainly composed of conductive carbon and a plasticizer mainly composed of dioctyl phthalate are appropriately adjusted at the time of blending, and the electric resistivity after molding is 2 × 10. ^Five Samples with JIS-A hardness of 30 ° and 22 ° aligned to Ωcm were prepared.
[0055]
Next, a resin tube produced using a tube molding method was provided as the conductive resin layer 13 on the conductive elastic layer 12. As the tube material, a polyvinyl chloride film produced by an inflation method was used. When the tube is coated, the outer diameter of the tube is 17.5 mm, and the outer fitting process is performed in which the roller having a diameter of 18 mm provided with the conductive elastic layer 12 on the conductive support 11 is inserted while the tube is expanded by wind pressure. Was used.
[0056]
The polyvinyl chloride film used for the conductive resin layer 13 is the type and amount of conductive carbon fine powder mixed for resistance adjustment in the film raw material, the type and amount of plasticizer mixed for elongation rate adjustment, By adjusting the kneading conditions and inflation processing conditions of these raw materials, film thickness, etc., the electrical resistivity is 3 × 10 ⁸ While aligning with Ωcm, samples having 10% elongation weights of 30 gf, 100 gf, 300 gf, 500 gf and 700 gf, respectively, were prepared. Separately, for the comparative experiment, samples having 10% elongation weights of 10 gf and 900 gf, respectively, in a 1 cm wide section prepared in the same manner were prepared. Here, a measurement method of the conductive resin layer 13 with respect to 10% elongation load in a 1 cm width section will be described.
[0057]
First, for the charging device 2 formed by sequentially laminating the conductive elastic layer 12 and the conductive resin layer 13 on the conductive support 11 manufactured as described above, the conductive resin layer portion is cut with an appropriate blade. The conductive resin layer slices having a width of 1 cm and a length of 6 cm were collected. Each section is chucked at 5 mm portions from both ends in the longitudinal direction, and a tensile load is applied to a portion having a width of 1 cm and a length of 5 cm in the longitudinal direction, and the elongation of the sample at that time is 10 with respect to a measurement length of 5 cm. The weight when 5% was obtained, which was 5%, was obtained, and this was defined as the 10% elongation weight Fgf in the 1 cm width section of the conductive resin layer 13 of the charging device 2.
[0058]
Here, when the conductive resin layer section cannot be collected with the above dimensions due to the convenience of the sample, the section width Wcm collected in a rectangular shape, the section length Lcm of the tensile test portion, the tensile load Tgf, and the tensile load are applied. From the section length L′ cm of the tensile test portion of
[0059]
[Expression 1]

[0060]
And 10% elongation weight Fgf in a 1 cm width section.
[0061]
In collecting the sample, the JIS-A hardness was measured for the conductive elastic layer after collecting the conductive resin layer slice, and the value was 30 ° or less of the original value of the conductive elastic layer. It was confirmed that the conductive resin layer could be collected according to the gist of the present invention. In addition, when a tube material is used as the conductive resin layer, it is possible to obtain an elongation load directly on the tube material before the outer fitting treatment, but the elongation due to the transformation of the material during the outer fitting treatment. Since a change in weight cannot be ignored, a method of cutting a conductive resin layer section from a final sample was used in this evaluation.
[0062]
Next, the construction of another embodiment of the charging device 2 in the copying machine will be described with reference to FIGS. FIG. 4 shows a transverse section of the charging device 2, and FIG. 5 shows a longitudinal section of the charging device 2. The charging device 2 has a configuration in which a conductive elastic layer 32, a conductive resin layer inner layer 33, and a conductive resin layer outer layer 34 are sequentially laminated on a conductive support 31.
[0063]
The feature of this configuration is that the conductive resin layer is formed of a plurality of layers of an inner layer and an outer layer. Specifically, as a conductive support 31, a metal shaft made of SUS303 having a diameter of 8 mm as described above is electrically conductive. A rubber layer mainly composed of 5 mm-thick ethylene propylene rubber having a JIS-A hardness of 30 ° and 22 ° similar to the above as the elastic elastic body layer 32 is produced as the conductive resin layer inner layer 33 by the same manufacturing method as described above. The charging device 2 was prepared by sequentially laminating the polyvinyl chloride film and the tetrafluoroethylene resin layer as the conductive resin layer outer layer 34 in order. This tetrafluoroethylene resin layer is obtained by spray-coating a commercially available tetrafluoroethylene resin coating solution (manufactured by Nippon Atchison Co., Ltd .: Emuralon 345) under a coating solution viscosity of 250 to 300 cp, and then 30 to 120 at 100 to 160 ° C. It was prepared by drying for a minute.
[0064]
Here, in addition to the preparation conditions of the polyvinyl chloride tube as described above, the two-layer structure is formed by adjusting the coating liquid viscosity, drying temperature, drying time, spray conditions, film thickness, etc. of the tetrafluoroethylene resin layer. The electrical resistivity of the entire conductive resin layer having 3 × 10 ⁸ While aligning with Ωcm, samples with 10% elongation weights of 30 gf, 100 gf, 300 gf, 500 gf, and 700 gf, respectively, were prepared.
[0065]
Separately, for the comparative experiment, samples having 10% elongation weights of 10 gf and 900 gf, respectively, in a 1 cm wide section prepared in the same manner were prepared.
[0066]
Various charging devices 2 manufactured as described above were mounted on a copying machine whose main configuration is shown in FIG. 1, imaged, and image quality evaluation was performed. The evaluation method is specifically described below.
[0067]
The charging device 2 is pressed into contact with the photosensitive member 1 at 2 kgf which does not adversely affect the contact, and the rotational peripheral speed of the photosensitive member, that is, the rotational peripheral speed of the charging device 2 that is driven to rotate, is commonly used in a high-speed copying machine. The ranges of 22 cm / sec, 38 cm / sec, and 60 cm / sec were selected, and the surface of the photoreceptor was initially charged to -600 V while adjusting the applied voltage in the range of approximately -1.0 to -1.2 kV. At this time, a commercially available surface potential meter (surface potential meter MODEL344 manufactured by TREK) was used for measurement of the photoreceptor surface potential.
[0068]
Next, a half original with a density of 0.4 is placed on the original platen, exposed from a position L in FIG. 1, developed by the developing device 3, and the obtained toner image is transferred to a transfer paper with a density of 0.03 for evaluation. An image sample for was obtained. At this time, the exposure amount was appropriately adjusted so that the maximum image density value in the image density evaluation described below was 1.0.
[0069]
The obtained image sample was obtained by using a commercially available image densitometer (Sakura Microdensitometer Model PDM-5TypeBR manufactured by Konica Corporation) in a scanning direction having a length of 10 cm corresponding to the circumferential direction of the photoconductor and a scanning speed of 50 times. The image density was measured under the conditions of 50 μm / second and a measurement area of 10 square μm. An image density difference was obtained from the maximum image density (1.0) measured at this time and the minimum image density, and correlated with sensory evaluation.
[0070]
Here, an image sample having an image density difference of 0.2 or less can be said to be an image that cannot visually recognize image density unevenness due to roller bounce, and such an image is referred to as rank A. An image sample with an image density difference of more than 0.2 and less than 0.35 can be said to be a practically acceptable image although it can be visually perceived to have uneven image density due to roller bounce. I decided to call it B. An image sample with an image density difference exceeding 0.35 can be said to be an image that is visually unfavorable because image density unevenness due to roller bounce can be recognized visually at a clear viewing distance. I decided to call it.
[0071]
Separately, in the copying machine whose main configuration is shown in FIG. 1, a durability test for passing 80,000 sheets of A4 paper was performed, and the durability of the charging device 2 was evaluated. The surface of the charging device 2 before and after the endurance test was observed with an optical microscope, and the charging device that showed sufficient durability with no change in the surface morphology was ranked X. The charging device that did not expose the conductive elastic layer was referred to as Rank Y, and the charging device in which micro-peeling occurred and even a slight exposed portion of the conductive elastic layer was observed was referred to as Rank Z.
[0072]
Tables 1 and 2 show the evaluation results for the various charging devices 2 obtained. Table 1 shows the evaluation results for the charging device 2 in which the conductive resin layer shown in FIGS. 2 and 3 is provided as a single layer, and Table 2 shows that the conductive resin layer shown in FIGS. 4 and 5 is provided in a plurality of layers. 3 is an evaluation result of the charging device 2. In the table, the term “elongation load” refers to a 10% elongation load in a 1 cm width section of the conductive resin layer.
[0073]
[Table 1]

[0074]
[Table 2]

[0075]
From the above results, in the roller-type contact charging device in a high-speed region that has a conductive elastic layer having a JIS-A hardness of 30 ° or less on a conductive support and is used by rotating at a peripheral speed of 20 cm / sec or more. By providing a conductive resin layer having a 10% elongation load of 700 gf or less on a 1 cm wide section on the conductive elastic layer, regardless of whether the configuration of the conductive resin layer is a single layer stack, it is due to roller elasticity. It can be seen that an image having non-practical problems with image density unevenness indicated by rank A and rank B can be obtained. Furthermore, when a conductive resin layer having a 10% elongation weight of 500 gf or less in a 1 cm wide section is provided, image density unevenness due to roller elasticity is ranked regardless of whether the configuration of the conductive resin layer is a single layer laminate. It can be seen that the optimum image indicated by A is obtained.
[0076]
On the other hand, from another purpose of durability, by providing a conductive resin layer having a 10% elongation weight of 30 gf or more in a 1 cm width section, regardless of whether the structure of the conductive resin layer is a single layer laminate, It can be seen that the roller surface form has practically satisfactory performance indicated by rank X and rank Y even after the durability test. Furthermore, by providing a conductive resin layer with a 10% elongation weight of 100 gf or more in a 1 cm wide section, the roller surface configuration is ranked X even after the endurance test, regardless of whether the conductive resin layer is a single layer laminate. It can be seen that it has the optimum performance shown in.
[0078]
【The invention's effect】
According to the present invention, even when used in a high-speed image forming apparatus, it is possible to prevent the occurrence of roller bounce unique to a contact charging device, so that image density unevenness is unlikely to occur and stable good charging is performed. Therefore, a highly reliable contact charging device can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a main part of a copying machine incorporating and using a charging device of the present invention.
FIG. 2 is a cross-sectional view of a basic configuration of a charging device according to the present invention.
FIG. 3 is a longitudinal sectional view of a basic configuration of a charging device according to the present invention.
FIG. 4 is a cross-sectional view of another configuration of the charging device according to the present invention.
FIG. 5 is a longitudinal sectional view of another configuration of the charging device according to the present invention.
[Explanation of symbols]
1: Photosensitive drum, 2: Charging device, 3: Developing device, 4: Transfer charger, 5: Cleaning device, 6: Eraser, 7: Intermediate roller pair, 8: Timing roller pair, 9: Conveyor belt, 11, 31 , 101: conductive support, 12, 32, 102: conductive elastic layer, 13, 103: conductive resin layer, 33: conductive resin layer inner layer, 34: conductive resin layer outer layer, 100: coil spring

Claims (5)

A contact charging device having a roller shape, which is used in an image forming apparatus in which the surface moving speed of an electrostatic latent image carrier is 22 cm / sec or more, and has a JIS-A hardness of 30 ° or less on a conductive support. An elastic elastic layer;
A resin film layer produced by a tube method having a 10% elongation load in a 1 cm width section of 30 gf to 700 gf , a thickness of 10 μm to 500 μm, and an electrical resistivity of 10 ⁷ Ωcm to 10 ¹¹ Ωcm. wherein, a contact charging apparatus characterized by sequentially laminating the conductive resin layer in contact with the electrostatic latent image bearing member.   The contact charging device according to claim 1, wherein the elongation load of the conductive resin layer is 100 gf or more and 500 gf or less. Contact charging apparatus according to claim 1 or claim 2, wherein the electrical resistivity of the conductive elastic layer is 10 ⁶ [Omega] cm or less. Contact charging device according to any one of claims 1 to 3 in which the thickness of the conductive elastic layer is characterized in that it is a 0.5 to 30 mm.   5. The contact charging device according to claim 1, wherein a pressure contact force of the contact charging device with respect to the electrostatic latent image bearing member is 0.5 to 3.0 kgf.

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